The present invention relates to tools for turning threaded fasteners such as bolts, nuts, studs, and the like, and more particularly relates to the use of wrench-type sockets for removing threaded fasteners that have heads that have been rounded off or otherwise damaged.
It is well known to use extraction tools to remove threaded fasteners that have been damaged. Typically, these tools are either used in conjunction with a socket wrench, or else a wrench may be placed around the periphery of the extraction tool in order to apply torque to remove the damaged fastener.
These tools often accomplish the extraction of a fastener through the use of xe2x80x9cteethxe2x80x9d made up of angled faces located within an opening in the tool. To remove a fastener, the teeth partially cut into and grasp the fastener. These types of extraction tools, however, often have shortcomings in the geometry of the teeth. The shape of the teeth may cause material from various fasteners to build up between the teeth, thus rendering the tool less effective. This, in turn, may require cleaning the teeth, which may be tedious and time-consuming.
Another problem associated with the shape of the teeth is that when a fastener is being extracted, the fastener may penetrate and thus cause damage to the angled faces that make up the teeth. This may result in an extraction tool having a significantly shorter useful life.
Extraction tools typically are designed to be attached to a socket wrench on one end, and to be placed over a fastener at the other end. Thus, one end of the tool typically will have an opening that must be sized to be compatible with the socket wrench, while the other end will have an opening that is sized to be placed over a fastener to be removed. This opening may need to be sized to accommodate very large fasteners. When this occurs, the extraction tool may be more difficult to fabricate, since it may require a pair of openings to each be machined into the tool whose sizes vary greatly from each other.
Accordingly, it would be desirable to have an extraction tool that overcomes one or more of the disadvantages and limitations described above.
To alleviate the disadvantages of the prior art, a fastener extractor is provided herein. The fastener extractor includes an attachment end having an attachment means for connection to an extraction tool and a receiving end having an interior bore angles inwardly towards the attachment end. The interior bore has a central axis and includes at least two arcuate grooves that extend along the interior bore towards the attachment end. The arcuate grooves curve radially and inwardly towards the central axis of the interior bore with adjacent arcuate grooves forming sharp helically shaped ridges. A transition area is positioned between the attachment end and the receiving end and has a plurality of arcuate surfaces. Each of the plurality of surfaces corresponds to each of the arcuate grooves and projects inwardly from the corresponding groove towards the central axis.
In another embodiment of the invention, a socket wrench assembly is provided that includes a socket tool having an outwardly projecting male structure. A fastener extractor is also included and is configured for engagement over a fastener to be extracted. The fastener extractor has a receptacle that receives the male structure at a first end and has a frusto-conical receiving area at a second end. The receiving area has a central axis and extends inwardly and angularly towards the first end. At least two arcuate grooves extend along an inner surface of the receiving area towards the first end. The arcuate grooves curve radially and inwardly towards the central axis and towards the second end, with adjacent arcuate grooves forming sharp helically shaped ridges. A transition area is positioned between the receptacle and the receiving area and has a plurality of arcuate surfaces. Each of the plurality of surfaces corresponds to each of the arcuate grooves and projects inwardly from the corresponding groove towards the central axis.
Another embodiment of the invention includes a fastener extractor with an attachment end having a square-shaped receptacle for connection to a socket wrench. There is a receiving end that has an interior bore that angles inwardly at four degrees to a transition area. The interior bore has a central axis and includes six arcuate grooves that extend along the interior bore to the transition area. The arcuate grooves curve radially and inwardly towards the central axis of the interior bore, with adjacent arcuate grooves forming sharp helically shaped ridges. The transition area is positioned between the attachment end and the receiving end and includes six arcuate surfaces. Each of the surfaces corresponds to an arcuate groove and projects inwardly from the corresponding groove towards the central axis.
The invention provides a fastener extractor that is configured for engagement over a fastener to be extracted and allows for the convenient removal of damaged fasteners. The fastener extractor may be utilized with generally available tools to impart a large gripping and disengaging torque, including in areas that are difficult to access. The foregoing and other features and advantages of the invention will become further apparent from the following detailed description of the presently preferred embodiments, read in conjunction with the accompanying drawings.